/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package fi.jasoft.qrcode.zxing;

/**
 * <p>
 * Represents a 2D matrix of bits. In function arguments below, and throughout
 * the common module, x is the column position, and y is the row position. The
 * ordering is always x, y. The origin is at the top-left.
 * </p>
 * 
 * <p>
 * Internally the bits are represented in a 1-D array of 32-bit ints. However,
 * each row begins with a new int. This is done intentionally so that we can
 * copy out a row into a BitArray very efficiently.
 * </p>
 * 
 * <p>
 * The ordering of bits is row-major. Within each int, the least significant
 * bits are used first, meaning they represent lower x values. This is
 * compatible with BitArray's implementation.
 * </p>
 * 
 * @author Sean Owen
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class BitMatrix {

    private final int width;
    private final int height;
    private final int rowSize;
    private final int[] bits;

    // A helper to construct a square matrix.
    public BitMatrix(int dimension) {
        this(dimension, dimension);
    }

    public BitMatrix(int width, int height) {
        if (width < 1 || height < 1) {
            throw new IllegalArgumentException(
                    "Both dimensions must be greater than 0");
        }
        this.width = width;
        this.height = height;
        this.rowSize = (width + 31) >> 5;
        bits = new int[rowSize * height];
    }

    /**
     * <p>
     * Gets the requested bit, where true means black.
     * </p>
     * 
     * @param x
     *            The horizontal component (i.e. which column)
     * @param y
     *            The vertical component (i.e. which row)
     * @return value of given bit in matrix
     */
    public boolean get(int x, int y) {
        int offset = y * rowSize + (x >> 5);
        return ((bits[offset] >>> (x & 0x1f)) & 1) != 0;
    }

    /**
     * <p>
     * Sets the given bit to true.
     * </p>
     * 
     * @param x
     *            The horizontal component (i.e. which column)
     * @param y
     *            The vertical component (i.e. which row)
     */
    public void set(int x, int y) {
        int offset = y * rowSize + (x >> 5);
        bits[offset] |= 1 << (x & 0x1f);
    }

    /**
     * <p>
     * Flips the given bit.
     * </p>
     * 
     * @param x
     *            The horizontal component (i.e. which column)
     * @param y
     *            The vertical component (i.e. which row)
     */
    public void flip(int x, int y) {
        int offset = y * rowSize + (x >> 5);
        bits[offset] ^= 1 << (x & 0x1f);
    }

    /**
     * Clears all bits (sets to false).
     */
    public void clear() {
        int max = bits.length;
        for (int i = 0; i < max; i++) {
            bits[i] = 0;
        }
    }

    /**
     * <p>
     * Sets a square region of the bit matrix to true.
     * </p>
     * 
     * @param left
     *            The horizontal position to begin at (inclusive)
     * @param top
     *            The vertical position to begin at (inclusive)
     * @param width
     *            The width of the region
     * @param height
     *            The height of the region
     */
    public void setRegion(int left, int top, int width, int height) {
        if (top < 0 || left < 0) {
            throw new IllegalArgumentException(
                    "Left and top must be nonnegative");
        }
        if (height < 1 || width < 1) {
            throw new IllegalArgumentException(
                    "Height and width must be at least 1");
        }
        int right = left + width;
        int bottom = top + height;
        if (bottom > this.height || right > this.width) {
            throw new IllegalArgumentException(
                    "The region must fit inside the matrix");
        }
        for (int y = top; y < bottom; y++) {
            int offset = y * rowSize;
            for (int x = left; x < right; x++) {
                bits[offset + (x >> 5)] |= 1 << (x & 0x1f);
            }
        }
    }

    /**
     * A fast method to retrieve one row of data from the matrix as a BitArray.
     * 
     * @param y
     *            The row to retrieve
     * @param row
     *            An optional caller-allocated BitArray, will be allocated if
     *            null or too small
     * @return The resulting BitArray - this reference should always be used
     *         even when passing your own row
     */
    public BitArray getRow(int y, BitArray row) {
        BitArray ba = row;
        if (ba == null || ba.getSize() < width) {
            ba = new BitArray(width);
        }
        int offset = y * rowSize;
        for (int x = 0; x < rowSize; x++) {
            ba.setBulk(x << 5, bits[offset + x]);
        }
        return ba;
    }

    /**
     * This is useful in detecting a corner of a 'pure' barcode.
     * 
     * @return {x,y} coordinate of top-left-most 1 bit, or null if it is all
     *         white
     */
    public int[] getTopLeftOnBit() {
        int bitsOffset = 0;
        while (bitsOffset < bits.length && bits[bitsOffset] == 0) {
            bitsOffset++;
        }
        if (bitsOffset == bits.length) {
            return null;
        }
        int y = bitsOffset / rowSize;
        int x = (bitsOffset % rowSize) << 5;

        int theBits = bits[bitsOffset];
        int bit = 0;
        while ((theBits << (31 - bit)) == 0) {
            bit++;
        }
        x += bit;
        return new int[] { x, y };
    }

    /**
     * @return The width of the matrix
     */
    public int getWidth() {
        return width;
    }

    /**
     * @return The height of the matrix
     */
    public int getHeight() {
        return height;
    }

    public boolean equals(Object o) {
        if (!(o instanceof BitMatrix)) {
            return false;
        }
        BitMatrix other = (BitMatrix) o;
        if (width != other.width || height != other.height
                || rowSize != other.rowSize || bits.length != other.bits.length) {
            return false;
        }
        for (int i = 0; i < bits.length; i++) {
            if (bits[i] != other.bits[i]) {
                return false;
            }
        }
        return true;
    }

    public int hashCode() {
        int hash = width;
        hash = 31 * hash + width;
        hash = 31 * hash + height;
        hash = 31 * hash + rowSize;
        for (int i = 0; i < bits.length; i++) {
            hash = 31 * hash + bits[i];
        }
        return hash;
    }

    public String toString() {
        StringBuffer result = new StringBuffer(height * (width + 1));
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                result.append(get(x, y) ? "X " : "  ");
            }
            result.append('\n');
        }
        return result.toString();
    }

}
